In subsea production, electrically operated apparatuses below sea level are typically supplied by power from sea- or land-based host facilities. The power is provided from the external sources to the subsea devices via cable conductors to submerged process control equipment, pumps and compressors, transformers, motors, and other electrically operated equipment. As these components are disposed subsea and are typically enclosed and protected by water-proof pressure vessels, power is provided by means of a cable termination and connector, which may be an electrical penetrator, designed to penetrate and provide power through a bulkhead.
In existing penetrator assemblies, the conductor pin of the penetrator is embedded in an insulator body, which may be seated in a penetrator housing and is sealed against the penetrator housing by means of O-rings, or other types of seals. In downhole applications the electrical penetrator must protect against the egress of production media. At operational pressures at and above several thousand psi the penetrator is subjected to immense differential pressure. This pressure requires a penetrator structure that is adapted to operate despite high differential pressures across seals over a wide range of operating temperatures.
In one embodiment an electrical penetrator may be used to power subsea electric submersible pump (ESP) equipment and the like which pump hydrocarbons in oil well installations, and also in other applications such as high pressure electrical penetrations and other penetrations to provide power to various types of subsea equipment. The penetrator extends through the wall or bulkhead of the vessel in which the equipment is located, and is normally connected to power cables at one end for connecting the equipment to an external power source. In an ESP application, the connection or penetrator cannot be isolated from the pumping pressure for practical reasons. This creates an extreme environment for the connector or penetrator in terms of pressure, temperature, chemical exposure, and high voltage. The penetrator must transfer power to the motor as well as maintain a pressure barrier for internal pressure created by the ESP. The temperatures seen at the reservoir may be increased due to injection fluid temperatures, processing, as well as resistive heating of the electrical elements. For certain topside applications, the penetrators must also be able to resist sustained intense heat from a hydrocarbon fire and maintain seal integrity in high temperature and material stress situations.
In a typical electrical penetrator or feedthrough arrangement, a one-piece conductor such as a conductive connector pin extends through a bore in an insulating sleeve or body, with appropriate seals brazed, bonded, or otherwise mechanically engaged between the outer body and pin at each end of the penetrator assembly. In the case of ceramic penetrators, unique challenges exist in manufacture and subsequent use of the penetrator, due to the different coefficients of expansion of the different materials used in the penetrator assembly. In one known arrangement, the seals comprise metal sealing sleeves which seal the insulating sleeve of ceramic or the like to the conductive connector pin body. When temperature varies from the temperature at which parts were assembled, the parts expand by different amounts due to differences in coefficient of thermal expansion. If not properly managed, the different rates of expansion for the different material parts may induce stress within the assembly, and may lead to failure of the penetration.
Existing systems, apparatuses, and methods for wet- and dry-mate connectors and for electrical penetrators and penetrator assemblies are known and are described in at least U.S. Pat. No. 7,959,454, entitled WET MATE CONNECTOR (Ramasubramanian et al.), U.S. Pat. No. 8,123,549, entitled MULTIPLE LAYER CONDUCTOR PIN FOR ELECTRICAL CONNECTOR AND METHOD OF MANUFACTURE (Jazowski et al.), U.S. Pat. No. 8,287,295, entitled ELECTRICAL PENETRATOR ASSEMBLY (Sivik et al.), and U.S. Pat. No. 8,968,018, entitled ELECTRICAL PENETRATOR ASSEMBLY (Sivik et al.), each of which are incorporated by reference herein in their entirety.
To operate safely, reliably, and efficiently, the penetrator system must feature some level of modularity. This modularity allows the system to be installed and tested in a controlled environment, and allows the system to be readily upgraded over the useful design life based on lessons learned in the field.